Vehicle component lifespan determination device

Abstract

The present invention provides a vehicle component lifespan determination device that can prevent components from reaching the end of their lifespan before their expected lifespan. [Solution] A vehicle component life determination device for determining the lifespan of a predetermined component mounted on a vehicle, comprising: reading the load acting on the predetermined component (step S1); determining whether the actual fatigue amount based on the load acting on the predetermined component is greater than a predetermined standard fatigue amount based on a predetermined load acting on the predetermined component (step S3); and determining that the inverter 3 will reach the end of its lifespan before the standard lifespan period if the actual fatigue amount is greater than the standard fatigue amount (step S4).

Description

Technical Field

[0001] This invention relates to an apparatus for determining the lifespan of components provided in a vehicle.

Background Art

[0002] Patent Document 1 describes a remaining component lifespan determination apparatus for estimating the remaining lifespan of a stationary battery that reuses a battery used in a vehicle. This remaining component lifespan determination apparatus calculates the actual discharge capacity and internal resistance from the voltage value, current value, etc. of the stationary battery. This remaining component lifespan determination apparatus stores a plurality of maps for estimating the remaining lifespan corresponding to the usage environment such as the temperature and installation location when using the stationary battery. It reads the map corresponding to the usage environment of the stationary battery and calculates the remaining lifespan time of the stationary battery based on that map, the actual discharge capacity, and the internal resistance. The calculated remaining lifespan time is displayed on a display unit, and when the user desires to improve the remaining lifespan, some modules constituting the stationary battery are replaced by a worker.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The remaining life determination device described in Patent Document 1 determines the remaining life of a battery based on a map corresponding to the stationary usage environment. In other words, it determines the remaining life of a battery on the premise that the battery will be used according to a predetermined usage method. However, the load acting on components mounted on a vehicle differs depending on the way the user drives the vehicle and the environment in which the vehicle is used. Therefore, it is difficult to prepare a map for determining the remaining life that assumes such driving methods and usage environments during the design phase. For example, if the driving method or usage environment places a high load on the components, the high load will continue to act on the components even after the remaining life is determined, and the fatigue accumulated in the components may increase. In such cases, the components may reach the end of their lifespan before the remaining lifespan that is assumed to be based on the predetermined usage method as described in Patent Document 1. In other words, the components may reach the end of their lifespan before the predetermined lifespan, such as the warranty period for the components.

[0005] This invention was made in view of the above-mentioned technical problems, and aims to provide a vehicle component lifespan determination device that can prevent components from reaching the end of their lifespan before their expected lifespan. [Means for solving the problem]

[0006] To achieve the above objective, this invention provides a vehicle component life determination device for determining the lifespan of a predetermined component mounted on a vehicle, comprising a controller for determining the lifespan of the predetermined component, the controller comprising: a usage history storage unit for storing the load acting on the predetermined component; a comparison unit for comparing a standard fatigue amount based on a predetermined load acting on the predetermined component with the actual fatigue amount based on the load acting on the predetermined component stored in the usage history storage unit; and a determination unit for determining that the predetermined component will reach the end of its lifespan before a predetermined standard lifespan period if the comparison unit determines that the actual fatigue amount is greater than the standard fatigue amount.

[0007] Furthermore, in this invention, the controller may estimate the load acting on the predetermined component based on the temperature of the predetermined component.

[0008] Furthermore, in this invention, the predetermined component includes an electronic component through which a current corresponding to the required driving force of the vehicle flows, and the controller may estimate the load acting on the predetermined component based on the driving force required of the vehicle.

[0009] Furthermore, this invention includes a cooling device that supplies a refrigerant to the predetermined component to cool it, and the controller may estimate the load acting on the predetermined component based on the temperature of the refrigerant in the cooling device.

[0010] Furthermore, in this invention, the controller may further include a life extension control execution unit that reduces the load acting on the predetermined component to a predetermined load if the determination unit determines that the predetermined component will reach the end of its life before the standard life period.

[0011] Furthermore, in this invention, the device further comprises a cooling device that supplies a refrigerant to the predetermined component to cool the predetermined component, the cooling device having a heat dissipation unit that dissipates heat from the refrigerant, and the controller may further comprise a life extension control execution unit that, when the lifespan of the predetermined component determined by the determination unit is shorter than a predetermined standard lifespan, increases the amount of heat dissipated by the heat dissipation unit to a predetermined amount of heat dissipation, or increases the flow rate of the refrigerant from the cooling device to a predetermined flow rate. [Effects of the Invention]

[0012] According to this invention, a standard fatigue amount based on a predetermined load acting on a predetermined part is compared with the actual fatigue amount based on the load acting on the predetermined part stored in the usage history memory unit. If the actual fatigue amount is greater than the standard fatigue amount, it is determined that the predetermined part will reach the end of its lifespan before the predetermined standard lifespan. Therefore, it is possible to determine whether the predetermined part will reach the end of its lifespan before the standard lifespan, taking into account factors such as the driver's operation and the vehicle's usage environment. [Brief explanation of the drawing]

[0013] [Figure 1] This figure schematically shows an example of a vehicle equipped with a component life determination device according to an embodiment of this invention. [Figure 2] This is a block diagram illustrating the functional configuration of a component life determination device in an embodiment of the present invention. [Figure 3] These are distribution diagrams illustrating an example of data processed by the learning unit: (a) is a distribution diagram processed with data on changes in element temperature, (b) is a distribution diagram processed with data on the rate of change of accelerator opening, and (c) is a distribution diagram processed with data on changes in coolant temperature. [Figure 4] These are graphs comparing data processed by the learning unit with reference data. (a) is a comparison graph of data on changes in element temperature, (b) is a comparison graph of data on the rate of change of accelerator opening, and (c) is a comparison graph of data on changes in coolant temperature. [Figure 5] This is a flowchart illustrating an example of control performed by the controller in this embodiment of the invention. [Modes for carrying out the invention]

[0014] This invention will be described based on the embodiments shown in the figures. The embodiments described below are merely examples of how this invention can be implemented and do not limit it.

[0015] An example of a vehicle Ve in an embodiment of this invention is schematically shown in Figure 1. The vehicle Ve shown in Figure 1 is equipped with a motor (MG) 1 as a driving force source. This motor 1 can be configured in the same way as motors provided as driving force sources in conventional electric vehicles and hybrid vehicles. That is, in addition to functioning as a motor that outputs driving torque when power is supplied, it is configured to function as a generator that converts at least a portion of its power into electricity by having an output shaft (not shown) rotated along with it. Specifically, it is an AC motor such as a synchronous motor or an induction motor.

[0016] A battery storage device (BATT) 2 is provided that functions as a power source for the motor 1 and is also capable of charging the electricity generated by the motor 1. This battery storage device 2 is composed of secondary batteries such as nickel-metal hydride batteries or lithium-ion batteries. In other words, the battery storage device 2 is composed of a DC power source. The battery storage device 2 may also be a battery pack in which multiple batteries are connected in series. Furthermore, the battery storage device 2 may include an electric double-layer capacitor.

[0017] The vehicle is equipped with an inverter (INV) 3 that converts the DC power output from the energy storage device 2 into AC power and outputs it to the motor 1, and also converts the AC power generated by the motor 1 into DC power and supplies it to the energy storage device 2. This inverter 3 is composed of multiple electronic components such as transistors and diodes (not shown), similar to inverters installed in conventional vehicles. The transistors may be insulated-gate bipolar transistors (IGBTs) or metal-oxide-semiconductor field-effect transistors (MOSFETs).

[0018] The above-described inverter 3 generates heat according to the value of the current flowing therethrough. Therefore, a cooling device 4 is provided to prevent the durability of the inverter 3 from deteriorating due to temperature rise. This cooling device 4 is configured to dissipate the heat of the inverter 3 to the cooling water through the case by flowing cooling water (refrigerant) around the case in which the inverter 3 is housed. In FIG. 1, a flow path 4a through which the cooling water flows is schematically shown by a broken line.

[0019] Further, the cooling device 4 is provided with a radiator 4b corresponding to the "heat dissipation part" in the embodiment of this invention. This radiator 4b can be configured in the same manner as a radiator provided in a vehicle equipped with an engine as a driving power source, is provided in the flow path 4a, and is disposed on the front side of the vehicle Ve. Therefore, the heat of the cooling water is dissipated to the air passing through the radiator 4b such as running wind. Note that the cooling device 4 may be provided with a pump (not shown) for controlling the flow rate of the cooling water.

[0020] A radiator fan 5 is provided on the rear side of the vehicle Ve of the radiator 4b. This radiator fan 5 is configured to rotate by a motor or the like (not shown). Therefore, by increasing the rotational speed of the radiator fan 5, the amount of air flowing through the radiator 4b can be increased. In other words, the amount of heat dissipated by the radiator 4b can be increased.

[0021] An electronic control device (hereinafter referred to as a controller) 6 for controlling the above-described inverter 3 and radiator fan 5 is provided. This controller 6 is mainly composed of a microcomputer, and outputs a command signal for controlling the inverter 3 and radiator fan 5 based on the input signal and a map or arithmetic expression stored in advance.

[0022] In the example shown in Figure 1, signals are input to the controller 6 from an element temperature sensor 7 that detects the temperature of the inverter 3 (specifically, the temperature of the electronic components), a water temperature sensor 8 that detects the temperature of the coolant, and an accelerator opening sensor 9 (not shown) that detects the amount of accelerator operation. The water temperature sensor 8 is positioned to detect the temperature of the coolant on the downstream side of the flow path 4a, in other words, just before it recirculates to the radiator 4b.

[0023] Furthermore, the controller 6 is configured to determine the lifespan of the electronic components constituting the inverter 3. A block diagram illustrating the functional configuration for determining the lifespan of these electronic components is shown in Figure 2. The controller 6 shown in Figure 2 includes a usage history storage unit 10, a learning unit 11, a comparison unit 12, a determination unit 13, and a life extension control execution unit 14. In the following description, the inverter 3, including the electronic components constituting it, will simply be referred to as the inverter 3. Note that the inverter 3, including the electronic components, corresponds to the "predetermined components" in this embodiment of the invention.

[0024] The usage history storage unit 10 stores the signals detected by the sensors 7, 8, and 9. These sensors 7, 8, and 9 detect parameters that affect the durability of the inverter 3. In other words, the usage history storage unit 10 stores the loads acting on the inverter 3.

[0025] Repeatedly increasing and decreasing the current supplied to inverter 3 reduces the durability of inverter 3 due to factors such as thermal stress from heat generation and cooling, which causes loads to act between materials with different coefficients of linear expansion. In other words, the load on inverter 3 can be estimated by detecting the temperature of inverter 3 with the element temperature sensor 7. Therefore, the usage history storage unit 10 stores the temperature of inverter 3 detected by the element temperature sensor 7 as the load acting on inverter 3.

[0026] Furthermore, the required driving force of the vehicle Ve changes according to the amount of accelerator operation, and consequently, the current supplied to the motor 1 (i.e., the current flowing through the inverter 3) changes. In other words, the load on the inverter 3 can be estimated by detecting the accelerator opening using the accelerator opening sensor 9. Therefore, the usage history storage unit 10 stores the accelerator opening detected by the accelerator opening sensor 9 as the load acting on the inverter 3.

[0027] Furthermore, the higher the temperature of the inverter 3, the higher the temperature of the cooling water. In other words, by detecting the temperature of the cooling water, the load acting on the inverter 3 can be estimated. Therefore, the usage history storage unit 10 stores the cooling water temperature detected by the water temperature sensor 8 as the load acting on the inverter 3.

[0028] The usage history storage unit 10 only needs to be able to store data related to the load acting on the inverter 3. For example, an ammeter may be provided on the output side of the inverter 3, and the current value detected by the ammeter may be stored as the load acting on the inverter 3.

[0029] The learning unit 11 learns the fatigue level of the inverter 3 (hereinafter referred to as the actual fatigue level) based on the data stored in the usage history storage unit 10. Specifically, it first generates data that can be used to create the histogram shown in Figure 3 based on the data stored in the usage history storage unit 10. Furthermore, as exemplified by power cycle tests, the limit of fatigue accumulated in the inverter 3 can be evaluated by the number of times the power supplied to the inverter 3 is increased and decreased within a predetermined time.

[0030] Figure 3(a) shows an example of a histogram (frequency distribution) where the change in element temperature is plotted as a class on the horizontal axis and the number of occurrences for each change in element temperature is plotted as the frequency on the vertical axis. Figure 3(b) shows an example of a histogram (frequency distribution) where the rate of change in accelerator opening is plotted as a class on the horizontal axis and the number of occurrences for each rate of change in accelerator opening is plotted as the frequency on the vertical axis. Figure 3(c) shows an example of a histogram (frequency distribution) where the change in coolant temperature is plotted as a class on the horizontal axis and the number of occurrences for each change in coolant temperature is plotted as the vertical axis.

[0031] Here, the change in element temperature is the difference between the minimum and maximum temperatures within a predetermined period, the rate of change in accelerator opening is the value obtained by dividing the difference between the minimum and maximum openings within a predetermined period by that predetermined period, and the change in coolant temperature is the difference between the minimum and maximum temperatures within a predetermined period.

[0032] The learning unit 11 then learns the actual fatigue amount by, for example, multiplying the frequency by a predetermined coefficient set in advance for each class in order to convert it into the fatigue amount corresponding to the above class.

[0033] The comparison unit 12 compares the actual fatigue amount learned by the learning unit 11 with the fatigue amount when the vehicle Ve is used based on the operating method and operating environment of the vehicle Ve predetermined during the design phase, i.e., under normal operation (hereinafter referred to as the standard fatigue amount). Specifically, the comparison unit 12 stores a predetermined load distribution that represents the fatigue limit of the inverter 3, obtained from power cycle tests during the design phase, and generates data that can be used to create a histogram for comparison with the actual fatigue amount learned by the learning unit 11, based on the stored load distribution, the service period until the end of its lifespan, and the service period at the present time.

[0034] Next, as shown in Figure 4, the histogram (solid line) based on the data stored in the usage history storage unit 10 is compared with the histogram (dashed line) based on the data generated by the comparison unit 12. In the example shown in Figure 4, the data stored in the usage history storage unit 10 exceeds the data generated by the comparison unit 12 in all classes.

[0035] As shown in Figure 4, the data stored in the usage history storage unit 10 does not necessarily exceed the data generated by the comparison unit 12 in all classes. In such cases, the actual fatigue amount and the standard fatigue amount can be compared by multiplying the difference in frequency for each class by a predetermined coefficient set for each class and accumulating these values. In other words, the comparison unit 12 may also obtain the difference between the actual fatigue amount and the standard fatigue amount by quantifying it.

[0036] The determination unit 13 determines whether the inverter 3 will reach the end of its lifespan before a predetermined standard lifespan, such as a component compensation period, based on the comparison of the actual fatigue amount and the standard fatigue amount performed by the comparison unit 12. Specifically, if the actual fatigue amount is greater than the standard fatigue amount, it is determined that the inverter 3 will reach the end of its lifespan before the standard lifespan. This is because it is assumed that the inverter 3 has accumulated fatigue beyond what was anticipated up to this point, and that heavy operating operations or driving environments will continue to act on the inverter 3.

[0037] The determination unit 13 may, for example, calculate a margin of fatigue by subtracting the actual fatigue amount from the fatigue amount that will determine the lifespan of the inverter 3 in advance during the design phase, divide that margin of fatigue amount by the actual fatigue amount, and multiply by the current service life to obtain a numerical value for the remaining lifespan of the inverter 3, and then determine whether the estimated lifespan obtained by adding the service life to that remaining lifespan is less than the standard lifespan.

[0038] The life extension control execution unit 14 performs life extension control to reduce the load on the inverter 3 when the determination unit 13 determines that the inverter 3 will reach the end of its life before the standard life period. Specifically, for example, compared to the case where it is determined that the inverter 3 will not reach the end of its life before the standard life period, the load acting on the inverter 3 is reduced by lowering the required drive torque of the motor 1 in response to the amount of operation of the accelerator device, or by reducing the amount of change in the torque of the motor 1.

[0039] Alternatively, if the determination unit 13 determines that the inverter 3 will reach the end of its lifespan before the standard lifespan, the life extension control execution unit 14 increases the amount of heat dissipated by the radiator 4b to a predetermined amount of heat dissipation that would be used if the inverter 3 were determined not to reach the end of its lifespan before the standard lifespan. Specifically, for example, the rotation speed of the radiator fan 5 is increased compared to the case where the inverter 3 is determined not to reach the end of its lifespan before the standard lifespan.

[0040] Alternatively, if the determination unit 13 determines that the inverter 3 will reach the end of its lifespan before the standard lifespan, the life extension control execution unit 14 increases the flow rate of the cooling water to a level higher than the predetermined flow rate used when it is determined that the inverter 3 will not reach the end of its lifespan before the standard lifespan. Specifically, for example, the discharge rate of the pump provided in the cooling device 4 is increased compared to the case where it is determined that the inverter 3 will not reach the end of its lifespan before the standard lifespan.

[0041] Furthermore, the decrease in the required drive torque of motor 1 in relation to the amount of operation of the accelerator device, the decrease in the change in the torque of motor 1, the increase in the rotational speed of radiator fan 5, or the increase in the discharge amount of the pump provided in the cooling device 4 may be determined according to the difference between the estimated lifespan and the standard lifespan.

[0042] Figure 5 shows a flowchart illustrating an example of the control performed by the controller 6 described above. In the control example shown in Figure 5, first, the temperature of the inverter 3, the accelerator opening, and the coolant temperature stored in the usage history storage unit 10 are read (step S1).

[0043] Next, the actual fatigue amount is learned (step S2). This step S2 is performed by the learning unit 11. That is, based on each data read from the usage history storage unit 10, data is generated that can be used to create the histogram shown in Figure 3, and the actual fatigue amount is learned based on that data.

[0044] Next, it is determined whether the actual fatigue amount is greater than the standard fatigue amount (step S3). If the judgment in step S3 is negative because the actual fatigue amount is less than the standard fatigue amount, it is considered that the load acting on the inverter 3 is small, and the driver's operation and the operating environment of the vehicle Ve are such that the load acting on the inverter 3 is small, and even if the current drive force control is maintained, the lifespan of the inverter 3 will not be shorter than the intended lifespan. Therefore, if the judgment in step S3 is negative, this routine is terminated for the time being.

[0045] Conversely, if the actual fatigue amount is greater than the standard fatigue amount and a positive judgment is made in step S3, it is considered that the load acting on the inverter 3 tends to be greater than the load specified in the design. In other words, the driver's operation and the operating environment of the vehicle Ve are considered to be driving operations or operating environments that place a high load on the inverter 3. Therefore, in the control example shown here, if a positive judgment is made in step S3, it is determined that the inverter 3 will reach the end of its lifespan before the standard lifespan (step S4).

[0046] In the control example shown in Figure 5, following step S4, the user is notified whether or not to switch to life-extension control by displaying it on a display unit 15 such as an instrument panel, and it is determined whether or not the user has selected to perform life-extension control (step S5). In other words, the controller 6 has a function to output a signal to the display unit 15 for selecting whether or not to perform life-extension control.

[0047] If the user does not choose to perform life-extension control, and the result in step S5 is negative, the routine is terminated. Conversely, if the user chooses to perform life-extension control, and the result in step S5 is positive, the life-extension control is performed (step S6), and the routine is terminated.

[0048] Step S6 is performed by the life extension control execution unit 14. Specifically, in order to reduce the load on the inverter 3, the required drive torque of the motor 1 in relation to the amount of operation of the accelerator device is reduced, or the amount of change in the torque of the motor 1 is reduced, compared to the case in which it is determined that the inverter 3 will not reach the end of its life before the standard life period. Alternatively, the rotational speed of the radiator fan 5 is increased, or the discharge amount of the pump is increased, compared to the case in which the estimated life is equal to or greater than the standard life.

[0049] As described above, the system compares the standard fatigue amount based on the design-defined load acting on the inverter 3 with the actual fatigue amount based on the actual load acting on the inverter 3 stored in the usage history memory unit. If the actual fatigue amount is greater than the standard fatigue amount, it is determined that the inverter 3 will reach the end of its lifespan before the standard lifespan. Therefore, it is possible to determine whether the inverter 3 will reach the end of its lifespan before the standard lifespan by taking into account factors such as the driver's operation and the operating environment of the vehicle Ve.

[0050] Furthermore, if the driver's operation requires a high load that was not intended during the design phase, or if the vehicle Ve is used in an environment that requires a high load that was not intended during the design phase, such as mountainous terrain, and the lifespan (estimated lifespan) of the inverter 3 becomes shorter than the standard lifespan, life extension control is performed to reduce the load on the inverter 3. As a result, it is possible to prevent the inverter 3 from reaching the end of its lifespan earlier than expected.

[0051] By implementing this life-extension control, changes in the drive torque of motor 1 are suppressed, acceleration responsiveness decreases, and the rotation speed of the radiator fan 5 increases, which may increase power consumption or increase abnormal noise. On the other hand, since the decision of whether or not to implement this life-extension control is left to the user, even if the above-mentioned changes in the behavior of vehicle Ve occur, it is possible to suppress the user from experiencing discomfort.

[0052] Furthermore, by configuring the system to enable life extension control, it becomes possible to discourage designing for high loads. As a result, it becomes possible to prevent the inverter 3 from becoming larger or more expensive, such as by increasing its durability in advance.

[0053] Furthermore, the component life determination device in this embodiment of the invention is not limited to determining the lifespan of an inverter, but may be any component that accumulates fatigue according to the driving load. Therefore, for example, it may determine the lifespan of a mechanical component that transmits torque from the drive source to the drive wheels. Also, the vehicle is not limited to an electric vehicle equipped with a motor, but may be a conventional vehicle equipped only with an engine as the drive source. [Explanation of symbols]

[0054] 1 motor 3 Inverter 4 Cooling device 4a Channel 4b Radiator 5. Radiator fan 6 Controllers 7-element temperature sensor 8. Water temperature sensor 9. Accelerator position sensor 10. Usage history storage unit 11. Learning Department 12 Comparison Section 13 Judgment section 14. Life extension control execution unit Vehicle

Claims

1. A vehicle component lifespan determination device for determining the lifespan of a predetermined component mounted on a vehicle, The system includes a controller that determines the lifespan of the predetermined component, The aforementioned controller, A usage history storage unit that stores the load acting on the predetermined component, A comparison unit that compares a standard fatigue amount based on a predetermined load acting on the predetermined part with the actual fatigue amount based on the load acting on the predetermined part stored in the usage history storage unit, If the comparison unit determines that the actual fatigue amount is greater than the standard fatigue amount, the determination unit determines that the predetermined part will reach the end of its lifespan before a predetermined standard lifespan. It is equipped with A vehicle component lifespan determination device characterized by the following features.

2. A vehicle component life determination device according to claim 1, The aforementioned controller, Based on the temperature of the predetermined component, the load acting on the predetermined component is estimated. A vehicle component lifespan determination device characterized by the following features.

3. A vehicle component life determination device according to claim 1, The aforementioned predetermined component includes an electronic component through which a current corresponding to the required driving force of the vehicle flows, The aforementioned controller, Based on the driving force required for the vehicle, the load acting on the predetermined component is estimated. A vehicle component lifespan determination device characterized by the following features.

4. A vehicle component life determination device according to claim 1, The system includes a cooling device that supplies a refrigerant to the predetermined component to cool it. The aforementioned controller, Based on the temperature of the refrigerant in the cooling device, the load acting on the predetermined component is estimated. A vehicle component lifespan determination device characterized by the following features.

5. A vehicle component life determination device according to claim 1, The aforementioned controller, The system further includes a life extension control execution unit that, if the determination unit determines that the predetermined component will reach the end of its life before the standard life period, reduces the load acting on the predetermined component to a predetermined load. A vehicle component lifespan determination device characterized by the following features.

6. A vehicle component life determination device according to claim 1, The system further includes a cooling device that supplies a refrigerant to the predetermined component to cool the predetermined component, The cooling device has a heat dissipation section that dissipates heat from the refrigerant, The aforementioned controller, The system further includes a life extension control execution unit that, if the lifespan of the predetermined component determined by the determination unit is shorter than a predetermined standard lifespan, increases the amount of heat dissipated by the heat dissipation unit to a predetermined amount of heat dissipation, or increases the flow rate of the refrigerant by the cooling device to a predetermined flow rate. A vehicle component lifespan determination device characterized by the following features.

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